To gain detailed information on the structure and dynamics of
the foliage within a canopy, the longevity of leaves of cacao trees
(Theobroma cacao L.) growing under normal commercial planting
shade in Bahia State, Brazil, was determined relative to their
position within the canopy and the time of leaf emergence.
In the experimental stand, the relative light intensity above the
cacao canopy ranged between 30 and 100% of full daylight, and
4–10% at ground level. The mean leaf area index for the canopy,
and the extinction coefficient of the foliage were 3·9 and
The longevity of leaves of adult trees of cacao with closely packed
crowns varied with their position within the canopy, and/or the
irradiance received, and the time of emergence. In particular
longevity decreased greatly with the height of the leaf from ground
level. The mean longevity for the upper foliage (more than 220 cm
above the ground) within the canopy was 181 d; the mean longevity of
the lower leaves (0–150 cm above the ground) was about twice
that of the upper leaves.
Approximately 23% of emergent leaves fell within 60 d of emergence,
following infection (about 14% of loss) or as a result of wind damage
(about 5% of loss). Thereafter, in mature and senescent leaves, leaf
fall followed normal physiological changes.